Earlier processes for preparation of cross-linked polyvinyl alcohol (PVA) sheets and films have involved a two-step method in which a dry film was first made and later cross-linked. Typical processes included treatment of a dry PVA film with an aldehyde-containing cross-linking solution or treatment with an acid solution of a dry PVA film in which an aldehyde cross linking agent was incorporated. Thus, these earlier processes require two distinct steps: (1) making of the PVA sheet or film; and (2) treatment with a solution to effect cross-linking. Rinsing and drying were also required after the cross-linking step.
It is an object of the present invntion to provide a novel method of producing cross-linked polyvinyl alcohol articles. It is a further object to provide such a process in which cross linking of the article is effected simultaneously with the formation of the article, thus avoiding the need of a separate cross linking step. It is a further object to provide cross-linked polyvinyl alcohol articles such as battery separators, made by the process.